Submarine signaling



Dec. 26, 1922. 1,440,360

UBMARINE GNALING. F: LED MAY 15 1922. 2 SHEETS'SHEET I IIIIIII 2 SHEETS'SHEET 2 F. L. PWOOD. SUFIMARINE SIGNALING Fl LED MAY 15. I 922.

Dec. 26, 1922.

WW5 717R: W in. 60W 55 7M M Patented Dec. 26, 1922:.

FRANK L. HOPWOOD, OF LoNDoN ENGLAND, ASSIGNOR T0 SUBMARINE SIGNAL COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

SUBMARINE SIGNALING.

Application filed May 15,

T 0 all whom it may concern Be it known that I, FRANK L. Horwoon, a subject of the King of England, and resident of London, in England, have invented a new and useful Improvement inexcited by compressional or sound waves or in any other way as by theefi'ect of electrical impulses so that they will send out compressional impulses.

Sharpness of tuning and sensitivity may be varied by varying the distance between the diaphragms so that efficiency may be varied at will. While I prefer that the diaphragms shall be backed with air or other gas, the chamber behind the diaphragm may in some cases be wholly or partially filled With any suitable accoustically transparent material.

My invention will be understood by reference to the drawings in which it is shown in its preferred forms.

Figure l is a vertical section through a transmitting apparatus constructed accordin r to my invention.

Fig. 2 is a modification thereof, and

Fig. 3 is a vertical section through a receiving apparatus also embodying my in vention,

Fig. 4 being a modification.

Referring to Fig. 1, the diaphragm 1 is mounted to close the end of a casing 2 containing an electro-magnet 3, the leads for Which are indicated by 4. In combination with this is arranged a diaphragm 5 mounted to close the end of a similar casing 6 in such a Way as to leave an air or other acoustic transparent space 7 behind the diaphragm. The diaphragms 1 and 5 above referred to are arranged with their faces Figure 2 is a similar view in which, however, the casing 6 also contains an electromagnet 3, the two electro-magnets being preferably arranged in series and energized to cause the diaphragms to vibrate syn- 1922. Serial No. 561,183.

chronously, in which case they will reinforce each other.

Figure 3 illustrates in vertical sectional; elevation two similar hydrophones 11, 11 with their diaphragms 12, 12 arranged facmg each other and parallel. 13 represents microphones which are fixed to the diaphragms in the usual way, 14: being the leads from the microphones. The details of construction of these hydrophones will be understood by those skilled in the art without further description.

By employing two hydrophones in the manner above described the advantage is obtained that should one hydrophone break down the other is available for reception in the ordinary manner, while at the same time each diaphragm serves to act as an intensifier to the other. This results from the fact that While a single diaphragm mounted to have its face in contact with water and backed by. air is highly damped, if two such diaphragms are mounted a suitable distance apart and facing-each other, one being set in vibration sets the other in vibration as though the water between them were a connecting rod so that they move together much as a single diaphragm if surrounded by air. Thus the instrument is more efficient and sensitive thanif a single diaphragm mounted like one of the shunts described above Were used alone. For the best re sults the distance between the diaphragms in any case can be readily determined by ex periment and may depend upon the materials used in constructing the instrument, etc. 1

What I claim as my invention is 1. An apparatus adapted for signaling comprising two independently mounted airfilled casings, each having anopening, diaphragms closing said openings whereby said diaphragms will be backed, said apparatus being arranged whereby said diaphragms shall be inparallel relation and in opposing relation and in proximity to each other whereby vibrations imparted to said diaphragms will reinforce each other. "2. An apparatus adapted for signaling comprising two independently mounted airfilled casings, each having an opening, diaing relation and in proximity to each other whereby vibrations imparted'rto said diaphragms will reinforce each other, and means for imparting vibrations to one of said diaphragms.

3. An apparatus adapted for signaling comprising two independently mounted airfilled casings, each having an opening, dia-f phragms closing said openings whereby said diaphragms Will be backed, said apparatus.

being arranged whereby said diaphragms shall be in parallel relation and in opposing relation and in proximity to each other whereby vibrations imparted to said diaphragms Will reinforce each other, means for impa rting vibrations to one of said diaphrag1ns',and means excited by said diaphragms whereby their vibrations may be transmitted to an indicator.

FRANK L. HOPVVOOD. 

